Question

Radha is drawing a dot Rangoli (a beautiful pattern of lines joining dots with chalk powder as shown in figure). She has $9$ dots in a row. How many dots will her Rangoli have for $r$ rows? How many dots are there if there are $8$ rows? If there are $10$ rows?

Answer 1

Given, number of dots in each row $=9$
Number of rows $=r$
$\therefore$ Total number of dots in $r$ rows $=9r$

Case 1: When number of rows $=8$

Number of dots in $r$ rows $=9r$

$\therefore$ Number of dots in $8$ rows $=9\times 8=72$

Case 2: When number of rows $=10$

Number of dots in $r$ rows $=9r$

$\therefore$ Number of dots in 10 rows $=9\times 10=90$